There are numerous methods available for imparting fire-retardant characteristics to plastics. Typical techniques include the addition of a phosphorous, antimony or halogen-containing compound to the plastic during the production stage. Some of these compounds are used in conjunction with one another: antimony compounds and halogen compounds are, in particular, frequently combined together to impart fire-retardant characteristics to melt produced plastics.
The efficacy of these fire retardants is determined by standardized testing procedures which measure the concentration of oxygen to which a treated plastic must be exposed in order to sustain burning. Any increase in the required oxygen concentration reflects improved fire-retardant properties for the composition being treated.
The present invention is based on applicant's discovery that the fire-retardant characteristics of a melt producable plastic composition which contains a usual fire-retardant additive such as a phosphorous, antimony, or halogen-containing compound can be enhanced by incorporating a glycoside into the composition. It is hypothesized that this result is achieved when the fire retardant compound catalyzes the dehydration of the glycoside, with a concomitant expenditure of energy. It is further hypothesized that the carbon remaining from the dehydration reaction forms a stable carbonaceous barrier, or char, which serves to prevent unburned material below the char from being exposed to combustion. The applicant, however, does not wish to be bound to any particular hypothesized mechanism for the novel result herein set forth.
Glycosides such as alpha-alkyl-dextro glycosides have been used heretofore as additives to thermoset plastics. For example, U.S. Pat. Nos. 2,773,788; 2,773,848 and 2,867,590 disclose the use of an alpha-alkyl-D-glucosides as a modifier in a thermosetting aminoplast resins such as melamine-formaldehyde resins and urea-formaldehyde resins. None of these references, however, discloses the use of alpha-alkyl-D-glucoside as a fire-retarding additive in a thermoplastic or otherwise melt produced plastic.
Derivatized alpha-alkyl-D-glucosides have also been used, not as an additive, but as the polyether polyol backbone in polyurethanes. It has been suggested that polyurethanes prepared in such a way are more fire resistant, but applicant is unaware of any information stemming from this art suggesting that glycosides be used as a fire retardant in melt produced plastics.